Vibration-responsive device



R. NORDENSWAN. vfsRATloN RESPONSIVE DEVICE.

APPLICATION FILED AUG.2. l9l7 I Patented Feb. 10, 1920.

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iUNITED STATES PATENT OFFICE.

vROIBERT NORDEN SWAN, OF NEW YORK, N. Y., ASSIG-NOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Application led August 2, 1917.

To all whom it may concern.'

Be it known that I, ROBERT NoRDENswAN, a subject of the King of Sweden, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Vibration-Responsive Devices, of which the following is a full, clear, concise, and exact description.

This invention relates to vibration responsive devices, and more especially to telephone receivers wherein the natural yfrequency of the diaphragm canbe varied over a considera'ble range.

The principal object of the invention is to provide a vibration 'responsive device in which the natural frequency of the diaphragm can be quickly and easily tuned or adjusted over a wide range of frequencies, and to this end, the diaphragm is held in fixed position and a member adjustable relatively thereto is provided to vary the effective area of the diaphragm and may also serve to further increase the range by varying the stress therein.

Referring to the drawing which illustrates one embodiment of the invention, Figure 1 is a plan view of a' telephone receiver with the cap and diaphragm thereof removed; Fig. 2 a vertical cross-section thereof on the line 2-2 of Fig. l; and Fig. 3 a view showing the application of a scale thereto to facilitate rapid adjustment.

.The receiver has an exterior threaded shell 1 of suitable non-magnetic material, the upper end 2 of which is of reduced diameter and extends partially across the shell 1 to provide an internal shoulder to which a magnet 3 is secured by screws 4f.

L-shaped pole pieces 5. and 6 are secured to opposite ends, respectively, of the magnet 3 at the lower side thereof, while a circular plate 7 of non-magnetic material serves to partition off the forward end of the shell 1, to form a magnet chamber and also alds to support the' pole pieces 5 and 6 firmly 1n place. The screws 4 extendmg through the plate, pole pieces and'magnet serve to hold these parts securely within the shell.

The lower end of the shell 1 1s closed by n, mp8; having a central perforation 9 therethrough for the passage of the usual con- Specication of Letters Patent.

Patented Feb. 10, 1920.

Serial No. 184,059.

ducting cord to the receiver, and is secured against movement by a set screw 10.

The plate 7 carries a hook 11 to which a strain relief strand of the conducting cord lmay 'be secured, and also carries three binding posts 12, 13 and 14; the post 12 being in electrical contact with the plate 7 to admit of grounding the receiver if desired; while the posts 13 and 14: are insulated from both sidesl of the plate 7 by insulation 15 and have pins 16 and 17 extending into the magnet chamber. Electromagnetic receiver coils 18 and19 connected in series are mounted on the pole pieces 5 and 6, respectively, and each have one end of their windings connected to the respective pins 16 and 17.

An outer cylindrical shell 2O is threaded for adjustment on the shell 1 and has an internal shoulder 2l which engages with a shoulder 22 on the shell 1 to limit the inward movement while a locking ring 23 may be used to lock the shells l and 20 in any desired relativ@J adjustment. Spanner openings 24 may be provided if desired to facilitate movement of the shell 20 relative to the ring 23. The u-pper end of the shell 20 is of reduced diameter and eXteriorly threaded to carry a receiver cap 25 which is screwed thereon, and serves to clamp a magnetic diaphragm 26 firmly thereto.

The upper end 2 of the shell 1 has a narrow non-resilient annular extension 27 designed to engage the diaphragm 26 to reduce the effective area thereof, when it is desired to tune the receiver to respond to higher frequencies than those to which the normal area of the diaphragm is responsive; the normal position being as shown in Fig. 2. The extension 27 can be made of various diameters relative to but less than the actual diameter of the diaphragm depending upon the particular range ofV frequencies to which it was desired to have the receiver responsive. If desired, one or more other adjustable members each having an annular extension similar to the extension 27 and adjusta-ble relatively thereto, so that any desired extension can be brought intov engagement with the diaphragm to limit the effective area thereof to that best suited for thepurpose in hand, may be provided.

One such member 28 is shown in its ciently belowthe top of the extension 27l so as not to interfere with the vibration of the 'diaphragm when the extension 27 is engaged therewith. ln the uppermost position of the member 28, the extension 29 extends sufficiently above extension 27 so that the latter will not interfere wlth the n diaphragm.

The member 28 is adjustable in the upper end 2 of the shell l and in its lowermost position abuts. the magnet 3 while a shoulder 30 on the end 2 limits its upward movement to position the extension 29 for operative engagement with the diaphragm 27. Any suitable means may be used to normally hold the member 28 in its upper and lower positions; a spring pin 31 and recesses 32 being shown for this purpose, while spanner grooves 33 may be provided on the member y28 to facilitate movement thereof.

In addition to varying the effective area of the diaphragm, the annular extension 27 or 29 may be used to stress or bow the diaphragm and to vary the stress therein to more perfectly tune it to any desired frequen-cy. ln order to prevent too great a stress being placed on the diaphragm and giving it a permanent set, the shoulders 2l and 22, and the member 28 and shoulder 30, respectively are arranged to engage and limit further movement before the pressure between theextension 27 'or 2 9 respectively and the diaphragm 'becomes sufficiently great to injure the latter.

When the effective area of the diaphragm isv reducedy as previously explained, it is preferable that the annular portion beyond the eective area thereof vibrate as little as possible and to overcome this an annular Washer 34 of felt or other suitable material may be arranged between the receiver cap 25 and diaphragm 26 to overlie at least part of the non-edective area. As shown it overlies all the non-effective area when the extension 27 is -used, and serves as adamping means to non-effective portions of the diaphragm when either the extension 27 or 29 is engaged therewith. The washer 34 is of such thickness that it will not normally exert suflicient pressure on the diaphragm to affect its natural period of vibration,

nor appreciably affect its amplitude of movement, but on the diaphragm being stressed orA bowed by the pressure of the extension 27 or 29, the washer is sutliciently compressed to eHectually dampen the non-eective portion of the diaphragm.

The receiver construction shown can be satisfactorily employed with voice currents' within the usual frequency range, by properly adjusting the air gap between the pole pieces and diaphragm, and without engagi ,seater ing either of the extensions therewith; but for higher ranges of frequency, it is necessary for efficient operation to engage the extension 27 or 29 with the diaphragm to reduce the e'ective area thereof and to produce the degree of stress therein best suited to the desired frequency.

It is often desirable to quickly duplicate an adjustment which has been previously found by experiment to be satisfactory. 'lo facilitate this, a portion of the thread on the shell 1 is removed as shown in Fig. 3 and a longitudinal scale 35 placed on the shell to indicate the position of the locking ring 23, while a scale 36 is arranged circumferentially of the shell 2() to admit of a micrometer adjustment thereof; an index line 37 being provided on the cover 8 for this purpose. ln this Way, the best position for each of the variety of conditions encountered would be determined experimentally and the reading of the scale noted for future reference and when it was desired to use the receiver again under like conditions, the parts would be directly adjusted to this position without further experiment by duplicating the scale position of the parts as previously determined.

What is claimed is:

l. ln a vibration'responsive device, a vibratory diaphragm, sup orting means therefor clamping said diap ragm substantially at the periphery thereof, and means to vary the effective vibratory area of said diaphragm to tune it to respond to a desired frequency.

2. In a vibration responsive device, a vibratory diaphragm, supporting means therefor clamping said diaphragm substantially at the periphery thereof, and means to vary the effective area and the stress in said diaphragm to tune itto respond to a desired frequency.

3. ln a vibration responsive device, a vibratory diaphragm, supporting means therefor, means to vary the effective'area of said diaphragm to tune it to respond to a certain frequency, andmeans to dampen the vibration of the `diaphragm within such areas as may be rendered non-effective by said area varyin means.

4. In a vibration responsive device, a"vi bratory diaphragm, means to support said diaphragm, means to engage with and vary the normal effective area of said diaphragm to 'tune it to respond to a desired frequency, and means to dampen the vibration of the diaphragm within such areas as may be .rendered non-effective by said area varying means; said damping means being operative only when the normal effective area of said diaphragm is changed.

5. ln a vibration responsive device, a vibratory diaphragm, supporting means therefor, means at one side of said diaphragm to vary the effective area thereof, and means at'the other side of said diaf vphragm to dampen the vibration thereof l operative only when said area varying means is engaged with the diaphragm.

7. In a vibration responsive device, a vibratory diaphragm, supporting means therefor clamping said diaphragm substantially at the periphery thereof, and a nonresilient member adjustable relative to said diaphragm to vary the effective vibratory area thereof to tune it to respond to adesired frequency. j

8. In a vibration responsive device, a vibratory diaphragm, supporting means therefor, and a member having ya non-resilient annular portion adjustable into and out of engagement with said diaphragm to vary the effective area thereof to tune said diaphragm to respond to different desired frequencies.

9. In a vibration responsive device, a vibratory diaphragm, supporting means therefor, and means movable into and out of engagement with said diaphragm to provide a plurality of effective vibratory areas for said diaphragm different from the normal effective area thereof to tune said diaphragm to respond to different desired frequencies.

10. In a telephone receiver, a vibratory diaphragm, supporting means therefor, means having a portion adjustable relative to said supporting means movable into and out of enga ement with said diaphragm to vary the eiictive area thereof to tune said diaphragm to respond to different desired frequencies, and a receiver magnet adjustable with said area varying means.

11. In a telephone receiver, a vibratory diaphragm, supporting means therefor, a

magnet casing adjustable relative to said diaphragm, an electromagnet having a pole piece within said caslng, and an annular Aflange associated with said casing and adjustable to engage said diaphragm to reduce the eifective area thereof; said magnet being mounted to maintain the pole piece thereof a fixed distance below the top edge of said flange. A

12. In a vibration responsive device, `a vibratory diaphragm, 'supporting means therefor, a member adjustable relative to said diaphragm to engage with and change' the effective area from the normal effective area thereof, and a second member adjust- -able'relative to said first member to engage with said diaphragm to provide an effective area different from that provided by said n first member.

v13. In a vibration responsive device, a vibratory diaphragm, supporting means therefor, a member adjustable `relative to said diaphragm having an annular portion to engage with and change the effective area from the normal effective area thereof, and a second member carried by and adjustable relatively to said first member and having an annular portion to engage said dia'- phragm to provide an eifective area diii'erent from that provided by said first member..

14. In a vibrationA responsive device, a vibratory diaphragm, supporting means therefor, a' member adjustable relative to said diaphragm having an annular portion to engage with and change the effective area thereof, a second member having an annular portion, and a member adjustable relative to said first member to position said annular portion above the annular portion .of said first member whereby either of said members may be adjusted to engage said diaphragm.

.15. In a vibration responsive device, a vrbratory diaphragm, supporting means therefor, a member adjustable relative to sald diaphragm having an annularY portion to engage with and to change the effective area of said diaphragm, and a second member secured to said first member having an annular portion thereon; said second member being operable to adjust said portion above and below the annular portion of said first member whereby either of said members may be adjusted -to engage said diaphragm.

In witness whereof, I hereunto subscribe my name this 1st day of August, A. D. 1917.

ROBERT NORDENSWAN. 

